Projected television device and screen

ABSTRACT

A front projection display device is provided including an image-generating source configured to generate an image, a wide angle lens system adapted to receive the image, and a screen. The wide angle lens system may be configured to increase distortion of the image in a first stage and decrease distortion of the image in a second stage. The screen may be configured to receive the image from the wide angle lens system on a first side and reflect the image back to a viewer on the first side. In another embodiment, a screen is provided for a front projection system, the screen may be configured to receive light from a steep angle and may include any number of surface topographies configured to reflect light back to the viewer along a desired viewing plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of application Ser. No. 14/942,568 filed Nov. 16,2015, which is a Continuation of application Ser. No. 11/639,872 filedDec. 15, 2006, which is a Continuation of application Ser. No.10/754,093 filed Jan. 6, 2004, which is a Continuation-In-Part ofapplication Ser. No. 10/222,083 filed Aug. 16, 2002 (now U.S. Pat. No.6,896,375), and a Continuation-In-Part of application Ser. No.10/222,050 filed Aug. 16, 2002 (now U.S. Pat. No. 7,009,765). Thedisclosures of the prior applications are hereby incorporated byreference herein in their entireties.

BACKGROUND

There are many ways of projecting or displaying an image on a displaysurface. One method of generating a large screen display is the use of aprojection device, such as a projection television. Two types ofprojection televisions are rear projection televisions and frontprojection televisions. Typically, the components of a rear projectiontelevision are contained in a single unit. In contrast, with a frontprojection television, the components of the television may be separatedfrom each other. For example, in some front projection televisionsystems, some of the components may be disposed in a first location,while another components may be disposed at a second location.

Components of projection televisions typically include a projector and ascreen. An image may be generated by the projector and displayed on thescreen. The type of projector and/or screen, or combination thereof, mayaffect the quality of a displayed image.

SUMMARY

A front projection display device is provided including animage-generating source configured to generate an image, a wide anglelens system adapted to receive the image, and a screen. The wide anglelens system may be configured to increase distortion of the image in afirst stage and decrease distortion of the image in a second stage. Thescreen may be configured to receive the image from the wide angle lenssystem on a first side and reflect the image back to a viewer on thefirst side. In another embodiment, a screen is provided for a frontprojection system, the screen may be configured to receive light from asteep angle and may include any number of surface topographiesconfigured to reflect light back to the viewer along a desired viewingplane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a conventional front projectiondisplay device.

FIG. 2 is another schematic illustration of another front projectiondisplay device according to an embodiment of the present disclosure.

FIG. 3 is a block diagram of a lens system that may be used in the frontprojection display device of FIG. 2 according to an embodiment of thepresent disclosure.

FIG. 4 is a schematic illustration of a lens system that may be used inthe front projection display device of FIG. 2 according to an embodimentof the present disclosure.

FIG. 5 is a schematic illustration of another lens system that may beused in the front projection display device of FIG. 2 according to anembodiment of the present disclosure.

FIG. 6 is an illustration of a Fresnel screen for use with the frontprojection display device of FIG. 2.

FIG. 7 is a cross-sectional view of the Fresnel screen of FIG. 6according to an embodiment of the present disclosure.

FIG. 8 is another cross-sectional view of a configuration of a screenincluding a reflective back mirror for use with the front projectiondisplay device of FIG. 2 according to an embodiment of the presentdisclosure.

FIG. 8A is another cross-sectional view of a configuration of a screenincluding a lenticular sheet for use with the front projection displaydevice of FIG. 2 according to an embodiment of the present disclosure.

FIG. 9 is another cross-sectional view of a configuration of a screenincluding bead structures for use with the front projection displaydevice of FIG. 2 according to an embodiment of the present disclosure.

FIG. 10 is another cross-sectional view of a configuration of a screenincluding reflective bumps for use with the front projection displaydevice of FIG. 2 according to an embodiment of the present disclosure.

FIG. 11 is a schematic illustration of another lens system that may beused in a front projection display device of FIG. 2 according to anembodiment of the present disclosure,

FIG. 12 illustrates a projector with the lens system shown in FIG. 11according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

A display device incorporating an optical system capable of producing alarge image within a short distance is described below. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide a thorough understanding of the invention.It will be apparent, however, to one skilled in the art that theinvention can be practiced without these specific details. In otherinstances, structures and devices are shown in block diagram form inorder to avoid obscuring the invention.

FIG. 1 illustrates a conventional front projection display device. Frontprojection display device 100 includes a projector 110 and a screen 120.Screen 120 may be any suitable display surface. For example, in someembodiments, screen 120 may be a Fresnel screen. Typically, screen, 120includes a screen surface 130.

During operation of front projection display 100, projector 110 may beconfigured to generate an image and project the image on to screen 120.Screen 120 may reflect the projected image and direct it toward a viewer(not shown). In some embodiments, screen surface 130 may scatter lightso that the projected image is visible to the viewer. Rays 140 and 150illustrate exemplary paths that light may travel from projector 110 toscreen 120, while rays 160 and 170 illustrate exemplary paths that lightmay travel after reflecting off of screen 120.

Various types of screen surfaces with variable topography may be used toreflect an image toward a viewer. For example, the screen surface may bea glass-bead screen surface or a bumpy screen surface. A glass-beadscreen surface typically has a plurality of small glass marbles embeddedin a transparent coating on the surface of screen 130. Such surfaces maybe inadequate for some types of projection systems, such as the systemdescribed in FIG. 2. Moreover, such glass-based screens andbumpy-surface screens may be difficult to clean, which may affect thequality of the image reflected off of such screens.

In some embodiments, light impinging screen 120 may be diffused back tothe viewer such that near retro-reflection occurs when light hits thesescreens at the proper angle. Retro-reflection is reflection in whichlight is returned in directions close to the direction from which itcame. Thus, light hitting such a screen almost straight onto the surfaceof the screen may be bent back in the direction of a viewer sitting infront of the screen. The use of such retro-reflection may be not bepossible in systems such as the system described in FIG. 2.

FIG. 2 illustrates schematically, at 200, another front projectiondisplay device. As described above, front projection display deviceincludes a projector 210 and a screen 220. Screen 220 may include ascreen surface 230.

Projector 210 may be configured to project light at a steep angle fromthe horizontal to screen 220. For example, projector 210 may be offsetfrom screen 220 such that light is projected onto screen 220 at an anglebetween approximately 30 to 80 degrees from the horizontal. The angle ofreflection may vary along the screen. Rays 240 and 250 illustrateexemplary paths that light may travel from projector 210 to screen 220.For exemplary purposes only, ray 240 is shown reflecting and diffusingoff of the screen at an angle 245. Angle 245 may be any suitable angle,such as an 80 degree angle. Similarly, ray 250 is shown reflecting offof the screen at angle 255. Angle 255 may be any suitable angle, forexample angle 255 may be a 30 degree angle. As with FIG. 1, rays 160 and170 illustrates the path that light may travel after reflecting off ofscreen 220. In such systems, retro-reflection may be inadequate todisplay an image to a viewer.

In one embodiment of the present disclosure, projector 210 may be awide-angle projector. One exemplary wide angle system which may beimplemented in a front projection system is described in U.S. patentapplication Ser. No. 10/222,050 entitled “WIDE Angle Lens System Havinga Distorted Intermediate Image” filed Aug. 16, 2002, which isincorporated herein by reference.

In one exemplary wide angle system, illustrated schematically in FIG. 3,the system 300 may include a relay lens stage 310 and a wide angle lensstage 320. Relay lens stage 310 may be configured to generate andproject an intermediate image 330 to wide angle lens stage 320. Wideangle lens stage 320 may be configured to generate and project correctedimage 340 for display on screen 350.

Intermediate image 330 may be considered a distorted image (I(D)) suchthat wide angle lens stage receives a predistorted image. The distortioncaused by wide angle lens stage is such that substantially all thedistortion of intermediate image 330 is compensated for (cancelled) bywide angle lens stage 320 to generate image (I(-D)). The reference(I(-D)) is intended to indicate an image without the distortion of theintermediate image. It should be appreciated that the distortion can beto the image shape and/or the focal plane.

For purposes of the present description, the term “distortion,” isintended to mean any change from the initial image inputted into thepredistortion system. For example, in some embodiments, a distortion inthe image includes an alteration in the shape of at least a portion ofthe image. The term “predistortion” is intended to mean an intentionaldistortion of an optical image that compensates for (i.e. issubstantially equal and opposite to) distortion generated by thewide-angle projection system. It will be appreciated that thepredistorted image may be presented in a variety of differentconfigurations depending on the type of downstream distortion for whichthe predistorted image is intended to compensate.

The system described in FIG. 3 may include additional optics (notshown). For example, the system may include one or more prisms, etc. todirect the image along a desired, light path. Moreover, there may be oneor more lenses configured to provide alter the intermediate image or thecorrected image.

FIG. 4 illustrates one exemplary embodiment of a wide angle systemdescribed above. As illustrated, the system may include a DMD 410adapted to provide an image to the lens system. An image can be providedto DMD 410 in any manner known in the art. DMD 410 may be configured toselectively reflect light from any suitable light source (not shown) tothe lens system. Other types of devices (e.g., microelectromechanicalsystems (MEMS), grating light valve (GLV), liquid crystal display (LCD),liquid crystal on silicon (LCOS)) may be used to provide an image to thelens system.

Although other devices may be used to provide an image to the lenssystem, in the illustrated embodiment, prism 420 directs the image torelay lens group 430. Relay lens group 430 projects the image from prism420 to prism 440 and distorts the image such that intermediate prism 440receives an intentionally distorted intermediate image.

In one embodiment, relay lens group 430 includes 9 lenses; however, anynumber of lenses can be used, based on, for example, the desireddistortion of the intermediate image, or the overall size of the lenssystem. The distortion to be caused by relay lens group 430 may be equaland opposite the distortion caused by wide angle lens group 450. In oneembodiment, the intermediate image is approximately a half circle imagein a warped image plane. In alternate embodiments, other types ofdistortion may be used. For example, if the full lens field is to beused, the distorted intermediate image would be a generally circularimage, The image plane may or may not be warped.

Intermediate prism 440 may provide a 90.degree., fold of the image path.As described below with respect to FIG, 5, the fold is not required.Alternatively, other fold angles, for example, 45.degree., 30.degree.,135.degree., 180.degree., etc. could be used. Moreover, multiple foldsmay be used as shown in FIGS. 11-12 and discussed in more detail below.Wide angle lens group 450 projects the distorted intermediate image to ascreen for display. Because wide angle lens group 450 causes distortionto the image to be projected and the intermediate image has beenpre-distorted by relay lens group 430, the resulting image projected bythe lens system has little or no distortion. In one embodiment, thetotal distortion caused by relay lens group 430, wide angle lens group450 and any associated prisms may be less than 3%.

In one embodiment, the optic axes of the lenses of relay lens group 430may be aligned. Similarly, the optic axes of the lenses of wide anglelens group 450 also may be aligned. Typically, wide angle lens groupprovides a field angle of greater than 100.degree. In one embodiment,the field angle is 153.degree.; however, any other angle can beprovided. In some embodiments, the optical axis of wide angle lens group450 is perpendicular to the screen so that keystone, or trapezoidaldistortion is absent.

FIG. 5 illustrates another embodiment of a wide angle lens system havinga distorted intermediate image. The lens system of FIG. 5 is similar tothe lens system of FIG. 4 except that the lens system of FIG. 5 is notfolded. That is, wide angle lens system 450 is co-axial with relay lenssystem 430. The lens system of FIG. 5 does not include an intermediateprism. An intermediate prism can be included, if desired.

As described above, the image may be projected to a screen. In someembodiments, the screen may be a portion of a Fresnel lens. FIG. 6illustrates a Fresnel lens 600 with exemplary outlines of sections, suchas the section indicated at 610 which may be used as a screen, althoughother sections may be used. The size and shape of the portion of thelens to be used corresponds to the size and shape of the screen of thedisplay device.

In one embodiment, Fresnel lens 600 can have many concentric grooveshaving one or more predetermined groove angles. There may be regions orzones with different groove angles. Techniques for manufacturing andusing Fresnel lenses having groove angle are known in the art.

FIG. 7 illustrates a cross-sectional profile of a screen for use in afront projection system. As schematically illustrated, screen 700 may bea Fresnel lens with, a plurality of grooves (peaks) on the screensurface. Each groove includes reflective facets 710 that are configuredto reflect impinging light (input light) 720 towards a viewer asindicated at 730. Such a configuration may accommodate light receivedfrom a steep angle, such as in the system shown in FIG. 2. If should benoted that the angle of the grooves and the reflection angle may vary toaccommodate the angle of the input light. Moreover, the opposing upwardfaces of the grooves may be adapted to prevent stray light from beingreflected toward the viewer.

It should be appreciated that the grooves may be substantially large toenable cleaning of the facets without damaging the surface of thescreen. In some embodiments, the surface of the screen may be charged torepel dust and other contaminants from collecting on the surface of thescreen. For example, a user-selectable device may be provided thatenables a charge to be sent through the surface of the screen, repellingany dust from the surface of the screen. Other methods may be providedfor cleaning screen 700. For example, forced air, including the use ofan air canister or air curtain, may be used to clean the screen.

Other types of screen surfaces and screens may be used to accommodate asteep angle projector as shown in FIG. 2. For example, the screen may bea lenticular screen. A lenticular screen may include multiple very smallhalf-cylindrical lenses (lenticules) spaced close together. In someembodiments, the lenticular screen may be a single-sided reflectivescreen, similar to the configuration shown in FIG. 7 for the Fresnelscreen. Thus, although FIG. 7 is described in relationship to use of aFresnel lens, it should be appreciated that the lens may be a lenticularscreen. Light may impinge the surface of such a lenticular screen at asteep angle and be reflected along a horizontal or other desired planeto a viewer.

FIG. 8 illustrates another embodiment for a screen for a frontprojection system at 800. The screen may be a single-sided fresnel lensor linear prism sheet and may include a mirror 810 or similar reflectivesurface on the back side of the screen. Input light 820 may pass throughthe face 830 of the lenses and may be slightly refracted 840. Therefracted light 840 may then be reflected off of a reflective surface(e.g. mirror) 810 and redirected back through the screen. The reflectedlight 850 may pass through the back side 860 of the lens toward theviewer, as indicated at 870.

In a similar embodiment, shown in FIG. 8A, the screen may be alenticular sheet, as shown at 860. The light 870 may pass through theface of the lenticules, be slightly refracted, reflected off the backwall, and redirected back through another lenticule.

Still in other embodiments, the lenticular screen may be double sided.For example, the front side of the lenticular screen may includehorizontal lenticules configured to change the vertical orientation ofthe light. The back side of the screen may include vertical lenticulesconfigured to change the horizontal, distribution of the light.

FIG. 9 further illustrates, at 900, another embodiment where the screensurface includes a plurality of glass bead type structures. The glassbeads may be configured to redirect the light depending on the entryangle of the input light. Thus, the shape of the beads may varydepending on the position of the beads in accordance with the angle ofinput light received. For example, in FIG. 9, input light 910 and 920 isdirected toward screen 900, Input light 910 and 920 impinge beads 930and 940, respectively. Beads 930 and 940 may be configured to redirectthe light outwards toward the viewer on a horizontal plane (as indicatedby 950 and 960 respectively). It should be appreciated that the entranceangle of light into the beads may vary along the vertical axis of thescreen. The refractive and reflective characteristics of the beads maycorrelate to the various entrance angles.

FIG. 10 further illustrates another screen surface 1000. As illustrated,the screen may have a plurality of reflective bumps or other suitablesurface topology. The bumps may be configured to receive input rays 1010and 1020 from a substantially steep angle and direct the light backtowards a viewer along a horizontal plane as shown by rays 1030 and 1040respectively.

The above screens may be configured to receive light from a steep angle,such as from the wide-angle lens systems described above. Each screenmay further be configured with surface topographies that are adapted toreflect light back to a viewer along a horizontal plane or othersuitable viewing plane.

It should be appreciated that each of the screen surfaces describedabove may be sized to prevent any significant interruption to the focusof the image. Moreover, it should be noted that the surfaces describedabove may be configured to be substantially durable such that thescreens can accommodate handling and touching by a user. Additionally,the screens surfaces may be configured to be easily cleaned. Forexample, coatings and other surface treatments may be applied to thescreen surface to reduce static, dust, etc and/or to protect thesurface. Moreover, the grooves and other surface topography may besubstantially sized to enable easy cleaning of the surface. In someembodiments, the screen surfaces may include anti-static coatings andother surface treatments to enhance image quality and durability of thescreen.

FIG. 11 further illustrates another exemplary lens system, indicatedgenerally at 1100. In the exemplary lens system, the image path includesmultiple folds. Specifically, the image path is directed through a firstrelay lens group 1110, through direction changing optics 1120, 1130 towide angle lens system 1140. In the illustrated configuration, light(the image path) is redirected by over 180 degrees. Any suitable opticalarrangement may be used to change the direction of light. In theexemplary embodiment, two fold mirrors or prisms 1120, 1130 may be usedso that the direction of light is changed by approximately 180 degrees.Other optical devices and number of folds of the image path may be usedwithout departing from the scope of the invention. For example, othercombinations of prisms and/or mirrors may be used to alter the imagedirection 180 degrees or more, The multiple fold arrangement reversesthe light direction such that output light is redirected in the same orsubstantially the same direction as input light (albeit differenthorizontal planes).

As with the lens systems described above, the lens system in FIG. 11 maybe configured to produce a distorted intermediate image. The distortionof the intermediate image may be corrected using a wide angle lens stagewhich may create distortion substantially equal and opposite to thedistortion of the intermediate image, In some embodiments, thedistortion of the intermediate image may be created by the use of arelay lens stage, as previously described.

Each of these lens systems may be considered to, have a predistortionsystem, such as the relay lens stage, which is configured to create apredistorted image (or intermediate image) from an original image. Thelens systems may further be understood to have a receiving projectionsystem, such as the wide angle lens system, which is configured toreceive the predistorted image and distort the image to substantiallycancel the predistortion of the predistorted image and to project asubstantially non-distorted image corresponding to the original image.

The lens system may be configured to direct the image 1150 from the wideangle lens stage to a screen. In some embodiments, the lens system maybe configured to direct the image to a screen at a steep angle. Forexample, the lens system may be configured to direct the light at anangle of 30 to 80 degrees toward a screen. The light may impinge thescreen on a first side and be redirected back toward a viewer on thesame side (first side) of the screen. Any suitable screen, such as thosedescribed above, may be used to receive the image from the lens system.

FIG. 12 further illustrates, at 1200, the use of the lens system (asshown in FIG. 11) with a projector 1210. As illustrated, the lens system1220 may be coupled to a projector. For example, the lens system may beremovably coupled to a projector. Alternatively, the lens system may beintegrated into a projector. By using the multiple fold system, thelength of the lens may be decreased creating a more compact system. Theorientation of the lens on the projector enables the main body of theprojector to be positioned in close proximity to a wall. Such aconfiguration may reduce the shelf space required for the projector whenin operation, while still providing the minimum throw distance requiredby the lens system. For example, the projector of FIG. 12 may be placedwithin 2 to 10 inches from a wall while producing a very large, 50-inchto 100-inch image.

The system of FIG. 12 further offsets the display device up. In contrastto some previous display systems, where the offset of the display deviceis down and the displayed image is offset up above the plane of theprojector, the present system is set such that the display device isoffset up in order to make the image offset up. For example, in someembodiments in the present system, the intermediate image produced bythe lens system may require an offset. For example, in FIG. 12, foldingthe lens and reversing the light direction may function to put thedisplay offset into a desired position.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and sub-combinations of the various elements, features,functions and/or properties disclosed herein. Where claims recite “a” or“a first” element or equivalent thereof, such claims should beunderstood to include incorporation of one or more such elements,neither requiring, nor excluding, two or more such elements.

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the invention. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the invention. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. A lens system using for a front projectiondisplay device comprising; a wide angle projection system having a firstlens stage to create a distorted intermediate image and a second, wideangle lens stage that causes distortion to substantially cancel thedistortion of the intermediate image and to project a substantiallynon-distorted image corresponding to the intermediate image at a fieldangle of greater than 100 degrees.
 2. The lens system of claim 1,wherein a fold mirror or prism folding an image path 90 degrees.
 3. Thelens system of claim 1, wherein two fold mirrors or prisms altering animage direction 180 degrees,.
 4. The lens system of claim 2, wherein anoptic axis of the first stage and an optic axis of the second stage forman angle of 90 degrees.
 5. The lens system of claim 3, wherein an opticaxis of the first stage and an optic axis of the second stage form anangle of 180 degrees.
 6. The lens system of claim 1, wherein the second,wide angle stage includes a wide-angle lens.
 7. The lens system of claim1, wherein the first stage includes a relay lens group.
 8. The lenssystem of claim 1, wherein the second, wide angle stage includes anoptical element of positive optical power.
 9. The lens system of claim1, wherein the second, wide angle stage includes a lens.